Bug 1881696 - Rework the ESLint environment so that eslint-plugin-mozilla is not enforcing the environment everywhere. r=frontend-codestyle-reviewers,Gijs

This makes it easier for subscribers of eslint-plugin-mozilla to use it more generally as a set of recommended
rules. The only environment definitions are for mozilla-specific file types, where we should be safe to specify
them.

Differential Revision: https://phabricator.services.mozilla.com/D225704

.eslintrc.js

@@ -54,6 +54,9 @@ module.exports = {
   ignorePatterns,
   // Ignore eslint configurations in parent directories.
   root: true,
+  env: {
+    es2024: true,
+  },
   // New rules and configurations should generally be added in
   // tools/lint/eslint/eslint-plugin-mozilla/lib/configs/recommended.js to
   // allow external repositories that use the plugin to pick them up as well.
@@ -64,6 +67,27 @@ module.exports = {
   ],
   plugins: ["mozilla", "html", "import", "json"],
   overrides: [
+    {
+      files: ["*.*"],
+      // The browser environment is not available for system modules, sjs, workers
+      // or any of the xpcshell-test files.
+      excludedFiles: [
+        "*.sys.mjs",
+        "*.sjs",
+        "**/?(*.)worker.?(m)js",
+        ...testPaths.xpcshell.map(filePath => `${filePath}**`),
+      ],
+      env: {
+        browser: true,
+      },
+    },
+    {
+      files: ["*.*"],
+      env: {
+        "mozilla/privileged": true,
+        "mozilla/specific": true,
+      },
+    },
     {
       files: [
         // All .eslintrc.js files are in the node environment, so turn that

tools/lint/eslint/eslint-plugin-mozilla/lib/configs/recommended.js

@@ -5,9 +5,17 @@
 "use strict";
 
 /**
- * The configuration is based on eslint:recommended config. The details for all
- * the ESLint rules, and which ones are in the recommended configuration can
- * be found here:
+ * The configuration is based on eslint:recommended config. It defines the
+ * recommended rules for all files, as well as for rules relating to modules
+ * and other module like files.
+ *
+ * The configuration intentionally does not specify the globals for the
+ * majority of files. The globals will only be specified for Mozilla specific
+ * files (e.g. system modules). The subscriber to this configuration is expect
+ * to include the correct globals that they require in their project.
+ *
+ * The details for all the ESLint rules, and which ones are in the ESLint
+ * recommended configuration can be found here:
  *
  * https://eslint.org/docs/rules/
  *
@@ -28,13 +36,6 @@
  *     - This doesn't reveal any actual errors, and is a lot of work to address.
  */
 module.exports = {
-  env: {
-    browser: true,
-    es2022: true,
-    "mozilla/privileged": true,
-    "mozilla/specific": true,
-  },
-
   // The prettier configuration here comes from eslint-config-prettier and
   // turns off all of ESLint's rules related to formatting.
   extends: ["eslint:recommended"],
@@ -45,7 +46,8 @@ module.exports = {
       // so we turn that off for those. Though we do have our own special
       // environment for them.
       env: {
-        browser: false,
+        "mozilla/privileged": true,
+        "mozilla/specific": true,
         "mozilla/sysmjs": true,
       },
       files: ["**/*.sys.mjs"],
@@ -101,10 +103,7 @@ module.exports = {
     },
     {
       env: {
-        browser: false,
-        "mozilla/privileged": false,
         "mozilla/sjs": true,
-        "mozilla/specific": false,
       },
       files: ["**/*.sjs"],
       rules: {
@@ -115,7 +114,6 @@ module.exports = {
     },
     {
       env: {
-        browser: false,
         worker: true,
       },
       files: [

tools/lint/eslint/eslint-plugin-mozilla/lib/configs/xpcshell-test.js

@@ -3,7 +3,6 @@
 
 module.exports = {
   env: {
-    browser: false,
     "mozilla/privileged": true,
     "mozilla/xpcshell": true,
   },